Escaping the House Game

The investigation led you to this building. On its door it said: "HOuse". It's a pretty obvious name indeed. It's even suspicious. You entered through the back door. As you reached the kitchen, you started to feel dizzy and in a few seconds your vision became blurry. Then you saw it. It was the only thing you could see clearly. A paper with a sentence on it. Hallucination Of USErs. You passed out. When you woke up everything became clear. On the door it was originally H.O.users, but the title was old. But the users of what? The air? Is it some kind of experiment? And how did you end up in a new house? Or is it just your mind tricking you?